What is the Dialog Id, and how do I get it?

Hi, I created a few controls (some edits, a button) inside my window using CreateWindow.
For the HMENU parameter, i just put in some arbitrary values I predefined. I assumed that this is the dialog id.
However, when I use functions like SetDlgItemText, the second parameter, int nIDDlgItem, does not accept that HMENU id I gave it upon creation. (the function fails with error code ERROR_CONTROL_ID_NOT_FOUND)